Showing papers on "Mass formula published in 2004"
TL;DR: In a wide class of unified models there is an additional term in the neutrino mass formula that under the simplest assumption takes the form M(nu)=(M(N)+M(T)(N))u/M(G), where M(N) is the neutRino Dirac mass matrix, and u=O(M(W)).
Abstract: In a wide class of unified models there is an additional (and possibly dominant) term in the neutrino mass formula that under the simplest assumption takes the form M(nu)=(M(N)+M(T)(N))u/M(G), where M(N) is the neutrino Dirac mass matrix, and u=O(M(W)). This makes possible highly predictive models. A generalization of this form yields realistic neutrino masses and mixings more readily than the usual seesaw formula in some models. The conditions for resonant enhancement of leptogenesis can occur naturally in such models.
146 citations
TL;DR: In this paper, the authors constructed a new mass table, referred to as HFB-8, including all the 9200 nuclei lying between the two drip lines over the range of $Z$ and $N\ensuremath{\geqslant}8$ and Z\ensemblemath{\leq slant}120$.
Abstract: Starting from HFB-6, we have constructed a new mass table, referred to as HFB-8, including all the 9200 nuclei lying between the two drip lines over the range of $Z$ and $N\ensuremath{\geqslant}8$ and $Z\ensuremath{\leqslant}120$. It differs from HFB-6 in that the wave function is projected on the exact particle number. Like HFB-6, the isoscalar effective mass ${M}_{s}^{*}$ is constrained to the value $0.80M$ and the pairing is density independent. The rms errors of the mass-data fit is $0.635\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$, i.e. better than almost all our previous HFB mass formulas. The extrapolations of this new mass formula out to the drip lines do not differ significantly from the previous HFB-6 mass formula.
105 citations
TL;DR: In this paper, it was shown that dominant spin-flavor interactions render certain parity-even states lighter than any pentaquark with all quarks in the spatial ground state.
41 citations
TL;DR: In this paper, a complete classification of qqqq¯q pentaquark states in terms of the spin-flavour SU(6) representations is presented, which is useful both for model builders and experimentalists.
Abstract: We construct a complete classification of qqqq¯q pentaquark states in terms of the spin-flavour SU(6) representations. We find that only some definite SU(3) representations are allowed, that is singlets, octects, decuplets, anti-decuplets, 27-plets and 35-plets. The latter three contain exotic states, which cannot be constructed from three quarks only. This complete classification is general and model independent and is useful both for model builders and experimentalists. The mass spectrum is obtained from a Gursey-Radicati type mass formula, whose coefficients have been determined previously by a study of qqq-baryons. The ground-state pentaquark, which is identified with the recently observed Θ+(1540) state, is predicted to be an isosinglet anti-decuplet state. Its parity depends on the interplay between the spin-flavour and orbital contributions to the mass operator.
40 citations
TL;DR: In this paper, the effect of the newly derived microscopic Hartree-Fock-Bogoliubov (HFB) mass formulae on r-process nucleosynthesis and analyze to what extent a solar-like r-abundance distribution can be obtained.
Abstract: The astrophysical origin of r-process nuclei is a long-standing mystery. Although some astrophysical scenarios show some promise, many uncertainties involved in both the astrophysical conditions and in the nuclear properties far from the β-stability have inhibited us from understanding the nature of the r-process. The purpose of the present paper is to examine the effects of the newly derived microscopic Hartree-Fock-Bogoliubov (HFB) mass formulae on r-process nucleosynthesis and analyze to what extent a solar-like r-abundance distribution can be obtained. The r-process calculations with the HFB-2 mass formula are performed, adopting the parameterized model of the prompt explosion from a collapsing O-Ne-Mg core for the physical conditions, and compared with the results obtained with the HFB-7 and droplet-type mass formulae. Because of its weak shell effect at the neutron magic numbers in the neutron-rich region, the microscopic mass formulae (HFB-2 and HFB-7) give rise to a spread of the abundance distribution in the vicinity of the r-process peaks (A = 130 and 195). While this effect resolves the large underproduction at A ≈ 115 and 140 obtained with droplet-type mass formulae, large deviations compared to the solar pattern are found near the third r-process peak. It is shown that a solar-like r-process pattern can be obtained if the dynamical timescales of the outgoing mass trajectories are increased by a factor of about 2-3, or if the β-decay rates are systematically increased by the same factor.
36 citations
TL;DR: In this paper, the authors examined the effects of the newly derived microscopic Hartree-Fock-Bogoliubov (HFB) mass formulas on the $r$-process nucleosynthesis and analyzed to what extent a solar-like $ r$-abundance distribution can be obtained.
Abstract: The astrophysical origin of $r$-process nuclei remains a long-standing mystery. Although some astrophysical scenarios show some promise, many uncertainties involved in both the astrophysical conditions and in the nuclear properties far from the $\beta$-stability have inhibited us from understanding the nature of the $r$-process. The purpose of the present paper is to examine the effects of the newly-derived microscopic Hartree-Fock-Bogoliubov (HFB) mass formulas on the $r$-process nucleosynthesis and analyse to what extent a solar-like $r$-abundance distribution can be obtained. The $r$-process calculations with the HFB-2 mass formula are performed, adopting the parametrized model of the prompt explosion from a collapsing O-Ne-Mg core for the physical conditions and compared with the results obtained with the HFB-7 and droplet-type mass formulas. Due to its weak shell effect at the neutron magic numbers in the neutron-rich region, the microscopic mass formulas (HFB-2 and HFB-7) give rise to a spread of the abundance distribution in the vicinity of the $r$-process peaks ($A = 130$ and 195). While this effect resolves the large underproduction at $A \approx 115$ and 140 obtained with droplet-type mass formulas, large deviations compared to the solar pattern are found near the third $r$-process peak. It is shown that a solar-like $r$-process pattern can be obtained if the dynamical timescales of the outgoing mass trajectories are increased by a factor of about 2-3, or if the $\beta$-decay rates are systematically increased by the same factor.
32 citations
TL;DR: The mass formula for nonexotic and exotic baryons is given as an expansion in 1/N(c) and allows one to relate the moment of inertia of the Skyrme soliton to the mass of a constituent quark.
Abstract: We derive the quantum numbers of baryon exotics in the quark model and the Skyrme model and show that they agree for arbitrary colors and flavors. We define exoticness E, which can be used to classify the states. The exotic baryons include the recently discovered qqqqq pentaquarks (E=1), as well as exotic baryons with additional qq pairs (E>/=1). The mass formula for nonexotic and exotic baryons is given as an expansion in 1/N(c) and allows one to relate the moment of inertia of the Skyrme soliton to the mass of a constituent quark.
24 citations
TL;DR: In this paper, the SU(3) mass relations among the pentaquark baryons in the anti-decuplet, when there is either no mixing or ideal mixing with the Pentaquark octet, were derived.
Abstract: We study the group structure of baryon anti-decuplet containing the $\Theta^+$. We derive the SU(3) mass relations among the pentaquark baryons in the anti-decuplet, when there is either no mixing or ideal mixing with the pentaquark octet, as advocated by Jaffe and Wilczek. This constitutes the Gell-Mann--Okubo mass formula for the pentaquark baryons. We also derive SU(3) symmetric Lagrangian for the interactions of the baryons in the anti-decuplet with the meson octet and the baryon octet. Our analysis for the decay widths of the anti-decuplet states suggests that the N(1710) is ruled out as a pure anti-decuplet state, but it may have anti-decuplet component in its wavefunction if the multiplet is mixed with the pentaquark octet.
16 citations
TL;DR: Yu et al. as mentioned in this paper generalize Gekeler's mass formula for supersingular Drinfeld modules from rational function fields to arbitrary global function fields, based on a calculation of Tamagawa numbers.
15 citations
TL;DR: In this paper, the ground state correlation energies associated with collective surface and pairing vibrations are calculated for Pb and Ca isotopes and it is shown that this contribution, when added to those predicted by one of the most accurate modern nuclear mass formulae (HFBCS MSk7 mass formula), reduces the associated rms error by an important factor, making mean field theory, once its time dependence is taken into account, a quantitative predictive tool for nuclear masses.
Abstract: The ground-state correlation energies associated with collective surface and pairing vibrations are calculated for Pb and Ca isotopes It is shown that this contribution, when added to those predicted by one of the most accurate modern nuclear mass formulae (HFBCS MSk7 mass formula), reduces the associated rms error by an important factor, making mean-field theory, once its time dependence is taken into account, a quantitative predictive tool for nuclear masses
13 citations
TL;DR: In this article, the presence of quantum chaos in nuclear mass systematics is analyzed by considering the differences between measured and calculated nuclear masses as a time series described by the power law 1 f α.
09 Jun 2004
TL;DR: In this article, a new nuclear mass formula composed of the gross term, the even-odd term, and the shell term is presented, which is a revised version of the spherical basis mass formula published in 2000.
Abstract: Some nuclear mass formulas are reviewed and applied for the heavy and superheavy nuclei A new mass formula composed of the gross term, the even‐odd term, and the shell term is also presented The new mass formula is a revised version of the spherical basis mass formula published in 2000, that is, the even‐odd term is treated more carefully, and a considerable improvement is brought about The root‐mean‐square deviation of the new formula from experimental masses is 641 keV for Z ⩾ 8 and N ⩾ 8 Properties on systematics of the neutron‐separation energies, alpha‐deacy Q‐values in the superheavy nuclidic region, and Q‐values of the fusion reaction for the heavy nuclei are compared with some mass formulas Furthermore, a method of estimation for fission half‐lives for the superheavy and neutron‐rich nuclei is presented With this estimation, the chart of nuclides for the nuclear decays are drawn, and the prediction of limit of the existence in the nuclidic region is discussed
TL;DR: In this paper, the deformed relativistic mean field theory was adopted as a framework and pairing correlations were treated by a simple BCS method with a zero-range δ-force.
Abstract: We perform a systematic study of all the traditional neutron magic nuclei with N = 8, 20, 28, 50, 82 and 126, from the neutron drip line to the proton drip line. We adopt the deformed relativistic mean-field theory as our framework and treat pairing correlations by a simple BCS method with a zero-range δ-force. Remarkable agreement with the available experimental data is obtained for the binding energies, the two- and one-proton separation energies, and the nuclear charge radii. The calculated nuclear deformations are compared with the available experimental data and the predictions of the FRDM mass formula and the HFBCS-1 mass formula. We discuss, in particular, the appearance of sub-shell magic nuclei by observing irregular behaviour in the two- and one-proton separation energies.
14 Sep 2004
TL;DR: The mass-loaded generalization of the Chew-Frautschi formula as discussed by the authors provides an essential tool for quantifying the mass differences of diquarks with different quantum numbers.
Abstract: It is plausible that several of the most profound aspects of low-energy QCD dynamics are connected to diquark correlations, including: paucity of exotics (which is the foundation of the quark model and of traditional nuclear physics), similarity of mesons and baryons, color superconductivity at high density, hyperfine splittings, $\Delta I = 1/2$ rule, and some striking features of structure and fragmentation functions. After a brief overview of these issues, I discuss how diquarks can be studied in isolation, both phenomenologically and numerically, and present approximate mass differences for diquarks with different quantum numbers. The mass-loaded generalization of the Chew-Frautschi formula provides an essential tool.
TL;DR: In this article, a modified Bethe-Weizsacker mass formula was proposed to describe minutely the positions of all the old and new magic numbers for neutrons and provided extra stability for some new neutron numbers.
Abstract: Proton and neutron separation energies are calculated using the extended Bethe–Weizsacker mass formula. This modified Bethe–Weizsacker mass formula describes minutely the positions of all the old and the new magic numbers. It accounts for the disappearance of some traditional magic numbers for neutrons and provides extra stability for some new neutron numbers. The neutron and proton drip lines are predicted using this extended Bethe–Weizsacker mass formula. The implications of the proton drip line on the astrophysical rp-process and of the neutron drip line on the astrophysical r-process are discussed.
TL;DR: In this paper, some properties of the modified Bethe-weizsacker mass formula (BWM) are discussed and compared with the experimental data, showing that if the shell effect quenches, the BWM predictions come closer to the test data.
Abstract: Some properties of the modified Bethe-Weizsacker mass formula (BWM) are discussed. As BWM has no shell effect included, the extra-stability or, magicity in nuclei clearly stands out when experimental mass data are compared with BWM predictions. If the shell effect quenches, the BWM predictions come closer to the experimental data.
TL;DR: In this paper, the presence of anomalous binding energies for the island of inversion centered at Z = 11, N = 21 is investigated by comparison of macroscopic binding energies and experiment.
Abstract: The presence of an anomaly in binding energies for the “island of inversion” centered at Z = 11, N = 21 is obtained by comparison of macroscopic binding energies and experiment. The macroscopic calculations were done with a mass formula deduced from the reformulation of the liquid-drop model of Myers et al. ; this formula is described in detail such as its predictions for binding energies of neutron-rich A = 29-44 nuclei. These calculations have indicated the presence of anomalies in the “island of inversion”. A weak-coupling approximation is applied to study this deformed region. The binding-energy values obtained using this model show the absence of these anomalies.
TL;DR: In this paper, the modified Bethe-Weizsacker mass formula with isotonic shifts was used to calculate the nuclear masses and predicted the neutron and proton drip lines.
Abstract: Nuclear masses are calculated using the modified Bethe-Weizsacker mass formula in which the isotonic shifts have been incorporated. The results are compared with the improved liquid drop model with isotonic shift. Mass excesses predicted by this method compares well with the microscopic-macroscopic model while being much more simple. The neutron and proton drip lines have been predicted using this modified Bethe-Weizsacker mass formula with isotonic shifts.
22 Sep 2004
TL;DR: In this article, the new narrow mesons observed recently in the final states Ds+π0 and Ds* +π0 are pointed out to be naturally assigned as the ground-state scalar and axial vector chiralons in the (cs) system, which would newly appear in the covariant hadron classifier.
Abstract: The new narrow mesons observed recently in the final states Ds+π0 and Ds*+π0 are pointed out to be naturally assigned as the ground‐state scalar and axial‐vector chiralons in the (cs) system, which would newly appear in the covariant hadron‐classification scheme proposed a few years ago.
01 Jan 2004
TL;DR: In this paper, the coefficients of the volume, surface, coulomb, asymmetry and pairing energy terms of the semi-empirical liquid drop model mass formula have been determined by furnishing best fit to the observed mass excesses.
Abstract: The coefficients of the volume, surface, coulomb, asymmetry and pairing energy terms of the semiempirical liquid drop model mass formula have been determined by furnishing best fit to the observed mass excesses. Slightly different sets of the weighting parameters for liquid drop model mass formula have been obtained from minimizations of chisquare and mean square deviation. The most recent experimental and estimated mass excesses from Audi-Wapstra-Thibault atomic mass table have been used for the least square fitting procedure. Equation of state, nuclear incompressibility, nuclear mean free path and the most stable nuclei for corresponding atomic numbers, all are in good agreement with the experimental results.
TL;DR: In this paper, a new set of relativistic mean field theory (RMFT) parameters, NL4, ensuring a better description of the average nuclear energy as given by the new Lublin-Strasbourg mass formula, is used in a self-consistent description of 171 spherical even-even nuclei at temperatures 0≤T≤4 MeV.
Abstract: A new set of relativistic mean-field theory (RMFT) parameters, NL4, ensuring a better description of the average nuclear energy as given by the new Lublin–Strasbourg mass formula, is used in a self-consistent description of 171 spherical even-even nuclei at temperatures 0≤T≤4 MeV. Single-particle level densities for this sample of nuclei are determined by analyzing the data obtained for various temperatures. The average dependence of the single-particle level density on mass number A and isospin is given and compared with previous estimates obtained using the RMFT-NL3, Thomas–Fermi and semiclassical Skyrme SkM* approaches.
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TL;DR: In this article, the coefficients of the volume, surface, coulomb, asymmetry and pairing energy terms of the semi-empirical liquid drop model mass formula have been determined by furnishing best fit to the observed mass excesses.
Abstract: The coefficients of the volume, surface, coulomb, asymmetry and pairing energy terms of the semiempirical liquid drop model mass formula have been determined by furnishing best fit to the observed mass excesses. Slightly different sets of the weighting parameters for liquid drop model mass formula have been obtained from minimizations of chisquare and mean square deviation. The most recent experimental and estimated mass excesses from Audi-Wapstra-Thibault atomic mass table have been used for the least square fitting procedure. Equation of state, nuclear incompressibility, nuclear mean free path and the most stable nuclei for corresponding atomic numbers, all are in good agreement with the experimental results.
TL;DR: In this paper, the Bethe-Weizsacker mass formula was extended to light nuclei and the results showed that it is less accurate compared to those by the macroscopic-microscopic calculations, and that such semi-empirical mass models can not be a substitute for more fundamental mass formulae having its origin based upon the basic nucleon-nucleon effective interaction.
Abstract: Some general features of the Bethe-Weizsacker mass formula recently extended to light nuclei have been explored. Though this formula improves fits to the properties of light nuclei and it does seem to work well in delineating the positions of all old and new magic numbers found in that region, yet it is not well tuned for predicting finer details. The mass predictions have also been found to be less accurate compared to those by the macroscopic-microscopic calculations. It is concluded that such semi-empirical mass formulae can not be a substitute for more fundamental mass formulae having its origin based upon the basic nucleon-nucleon effective interaction.
TL;DR: In this paper, a mass formula for light mesons was derived by combining the results of two methods: the dominantly orbital state description and the Bohr-Sommerfeld quantization approach.
Abstract: The quark dynamics inside light mesons, except pseudoscalar ones, can be quite well described by a spinless Salpeter equation supplemented by a Cornell interaction (possibly partly vector, partly scalar). A mass formula for these mesons can then be obtained by computing analytical approximations of the eigenvalues of the equation. We show that such a formula can be derived by combining the results of two methods: the dominantly orbital state description and the Bohr-Sommerfeld quantization approach. The predictions of the mass formula are compared with accurate solutions of the spinless Salpeter equation computed with a Lagrange-mesh calculation method.
TL;DR: In this paper, an extension of the Weizsacker mass formula is discussed, in which the pairing term is replaced with a Majorana term, which accounts for the spin-isospin symmetry of nuclei.
Abstract: An extension of the Weizsacker mass formula is discussed, in which the pairing term is replaced with a Majorana term. The Majorana term accounts for the spin-isospin symmetry of nuclei, which is related to Wigner’s SU(4) symmetry. This scheme is generalised to the simultaneous description of normal (i.e. non-strange) nuclei and Λ hypernuclei by extending the SU(4) symmetry to the SU(6) spin-flavour symmetry.
27 Jun 2004
TL;DR: A mass formula is derived of cyclic codes of length n= 2/sup e/ over the ring R/sub 4/= /spl Zopf// Sub 4/[x]/(x/sup n/-1) for a given length n.
Abstract: In this paper, we study cyclic codes of length n= 2/sup e/ over the ring R/sub 4/= /spl Zopf//sub 4/[x]/(x/sup n/-1) In particular, we derive a mass formula of these codes for a given length n We also give an example in which we study codes of length 8
TL;DR: The ground state correlation energies associated with collective surface and pairing vibrations are calculated for Pb- and Ca-isotopes as discussed by the authors, and it is shown that this contribution, when added to those predicted by one of the most accurate modern nuclear mass formula (HFBCS MSk7 mass formula), reduces the associated rms error by an important factor, making mean field theory, once its time dependence is taken into account, a quantitative predictive tool for nuclear masses.
Abstract: The ground state correlation energies associated with collective surface and pairing vibrations are calculated for Pb- and Ca-isotopes. It is shown that this contribution, when added to those predicted by one of the most accurate modern nuclear mass formula (HFBCS MSk7 mass formula), reduces the associated rms error by an important factor, making mean field theory, once its time dependence is taken into account, a quantitative predictive tool for nuclear masses.
01 Jan 2004
TL;DR: A mass formula is derived of cyclic codes of lengthq =2 h over the ringU 4 = Z4({)@({ q 3 1).
Abstract: In this paper, we study cyclic codes of lengthq =2 h over the ringU 4 = Z4({)@({ q 3 1). In particular, we derive a mass formula of these codes for a given lengthq= We also give an example in which we study codes of length 8=
01 Jan 2004
TL;DR: In this article, the authors used the extended Bethe{Weizsacker mass formula to calculate the positions of all the old and new magic numbers for neutrons and provided extra sta- bility for some new neutron numbers.
Abstract: Proton and neutron separation energies are calculated using the extended Bethe{ Weizsacker mass formula. This modied Bethe{Weizsacker mass formula describes minutely the positions of all the old and the new magic numbers. It accounts for the disappearance of some traditional magic numbers for neutrons and provides extra sta- bility for some new neutron numbers. The neutron and proton drip lines are predicted using this extended Bethe{Weizsacker mass formula. The implications of the proton drip line on the astrophysical rp-process and of the neutron drip line on the astrophysical r-process are discussed.
TL;DR: In this paper, an SU(3)F meson mass formula from random phase approximation is presented, and the mesons of ground-state pseudoscalar octet and ground state vector octet are described quite well.
Abstract: We present an SU(3)F meson mass formula from random phase approximation. Both the mesons of ground-state pseudoscalar octet and ground-state vector octet are described quite well by this mass formula. We also estimate the current and constituent quark masses from the naive quark model and the PCAC relation.